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From: Roberto Sassu <roberto.sassu@huawei.com>
To: <viro@zeniv.linux.org.uk>
Cc: <linux-security-module@vger.kernel.org>,
	<linux-integrity@vger.kernel.org>, <initramfs@vger.kernel.org>,
	<linux-api@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <zohar@linux.vnet.ibm.com>,
	<silviu.vlasceanu@huawei.com>, <dmitry.kasatkin@huawei.com>,
	<takondra@cisco.com>, <kamensky@cisco.com>, <hpa@zytor.com>,
	<arnd@arndb.de>, <rob@landley.net>, <james.w.mcmechan@gmail.com>,
	Roberto Sassu <roberto.sassu@huawei.com>
Subject: [PATCH v2 3/3] initramfs: introduce do_readxattrs()
Date: Thu, 9 May 2019 13:24:20 +0200
Message-ID: <20190509112420.15671-4-roberto.sassu@huawei.com> (raw)
In-Reply-To: <20190509112420.15671-1-roberto.sassu@huawei.com>

This patch adds support for an alternative method to add xattrs to files in
the rootfs filesystem. Instead of extracting them directly from the ram
disk image, they are extracted from a regular file called .xattr-list, that
can be added by any ram disk generator available today.

.xattr-list can be generated by executing:

$ getfattr --absolute-names -d -P -R -e hex -m - \
      <file list> | xattr.awk -b > ${initdir}/.xattr-list

where the content of the xattr.awk script is:

#! /usr/bin/awk -f
{
  if (!length($0)) {
    printf("%.10x%s\0", len, file);
    for (x in xattr) {
      printf("%.8x%s\0", xattr_len[x], x);
      for (i = 0; i < length(xattr[x]) / 2; i++) {
        printf("%c", strtonum("0x"substr(xattr[x], i * 2 + 1, 2)));
      }
    }
    i = 0;
    delete xattr;
    delete xattr_len;
    next;
  };
  if (i == 0) {
    file=$3;
    len=length(file) + 8 + 1;
  }
  if (i > 0) {
    split($0, a, "=");
    xattr[a[1]]=substr(a[2], 3);
    xattr_len[a[1]]=length(a[1]) + 1 + 8 + length(xattr[a[1]]) / 2;
    len+=xattr_len[a[1]];
  };
  i++;
}

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 init/initramfs.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/init/initramfs.c b/init/initramfs.c
index 98c2aa4b5ab4..91f35a84c592 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -11,6 +11,9 @@
 #include <linux/utime.h>
 #include <linux/file.h>
 
+#define XATTR_LIST_FILENAME ".xattr-list"
+
+
 static ssize_t __init xwrite(int fd, const char *p, size_t count)
 {
 	ssize_t out = 0;
@@ -451,6 +454,91 @@ static int __init do_setxattrs(void)
 	return 0;
 }
 
+struct path_hdr {
+	char p_size[10]; /* total size including p_size field */
+	char p_data[];  /* <path>\0<xattrs> */
+};
+
+static int __init do_readxattrs(void)
+{
+	struct path_hdr hdr;
+	char str[sizeof(hdr.p_size) + 1];
+	unsigned long file_entry_size;
+	size_t size, name_buf_size, total_size;
+	struct kstat st;
+	int ret, fd;
+
+	ret = vfs_lstat(XATTR_LIST_FILENAME, &st);
+	if (ret < 0)
+		return ret;
+
+	total_size = st.size;
+
+	fd = ksys_open(XATTR_LIST_FILENAME, O_RDONLY, 0);
+	if (fd < 0)
+		return fd;
+
+	while (total_size) {
+		size = ksys_read(fd, (char *)&hdr, sizeof(hdr));
+		if (size != sizeof(hdr)) {
+			ret = -EIO;
+			goto out;
+		}
+
+		total_size -= size;
+
+		memcpy(str, hdr.p_size, sizeof(hdr.p_size));
+		ret = kstrtoul(str, 16, &file_entry_size);
+		if (ret < 0)
+			goto out;
+
+		file_entry_size -= sizeof(sizeof(hdr.p_size));
+		if (file_entry_size > total_size) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		name_buf = vmalloc(file_entry_size);
+		if (!name_buf) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		size = ksys_read(fd, name_buf, file_entry_size);
+		if (size != file_entry_size) {
+			ret = -EIO;
+			goto out_free;
+		}
+
+		total_size -= size;
+
+		name_buf_size = strnlen(name_buf, file_entry_size);
+		if (name_buf_size == file_entry_size) {
+			ret = -EINVAL;
+			goto out_free;
+		}
+
+		xattr_buf = name_buf + name_buf_size + 1;
+		xattr_len = file_entry_size - name_buf_size - 1;
+
+		ret = do_setxattrs();
+		vfree(name_buf);
+		name_buf = NULL;
+
+		if (ret < 0)
+			break;
+	}
+out_free:
+	vfree(name_buf);
+out:
+	ksys_close(fd);
+
+	if (ret < 0)
+		error("Unable to parse xattrs");
+
+	return ret;
+}
+
 static __initdata int (*actions[])(void) = {
 	[Start]		= do_start,
 	[Collect]	= do_collect,
@@ -554,6 +642,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 		buf += my_inptr;
 		len -= my_inptr;
 	}
+	do_readxattrs();
 	dir_utime();
 	kfree(name_buf);
 	kfree(symlink_buf);
-- 
2.17.1


  parent reply index

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-09 11:24 [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk Roberto Sassu
2019-05-09 11:24 ` [PATCH v2 1/3] fs: add ksys_lsetxattr() wrapper Roberto Sassu
2019-05-10 21:28   ` Jann Horn
2019-05-09 11:24 ` [PATCH v2 2/3] initramfs: set extended attributes Roberto Sassu
2019-05-09 11:24 ` Roberto Sassu [this message]
2019-05-10 21:33   ` [PATCH v2 3/3] initramfs: introduce do_readxattrs() Jann Horn
2019-05-13 13:03     ` Roberto Sassu
2019-05-09 18:34 ` [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk Rob Landley
2019-05-10  6:56   ` Roberto Sassu
2019-05-10 11:49     ` Mimi Zohar
2019-05-10 20:46       ` Rob Landley
2019-05-10 22:38         ` Mimi Zohar
2019-05-11 22:44 ` Andy Lutomirski
2019-05-12  4:04   ` Rob Landley
2019-05-12  4:12     ` Rob Landley
2019-05-12  9:17 ` Dominik Brodowski
2019-05-12 10:18   ` hpa
2019-05-12 15:31     ` Dominik Brodowski
2019-05-13  0:02       ` Mimi Zohar
2019-05-13  0:21         ` hpa
2019-05-13  0:23       ` hpa
2019-05-12 12:52   ` Mimi Zohar
2019-05-12 17:05     ` Rob Landley
2019-05-12 19:43       ` Arvind Sankar
2019-05-13  7:49         ` Roberto Sassu
2019-05-13  9:07           ` Rob Landley
2019-05-13 12:08             ` Mimi Zohar
2019-05-13 12:47             ` Roberto Sassu
2019-05-13 17:20               ` Arvind Sankar
2019-05-13 17:51                 ` Arvind Sankar
2019-05-13 17:52                 ` Arvind Sankar
2019-05-13 18:36                   ` Mimi Zohar
2019-05-13 18:47                     ` Arvind Sankar
2019-05-13 22:09                       ` Mimi Zohar
2019-05-14  6:06                         ` Rob Landley
2019-05-14 14:44                           ` Arvind Sankar
2019-05-14  6:06               ` Rob Landley
2019-05-14 11:52                 ` Roberto Sassu
2019-05-14 15:12                   ` Rob Landley
2019-05-14 15:27                   ` Arvind Sankar
2019-05-14 15:57                     ` Arvind Sankar
2019-05-14 17:44                       ` Roberto Sassu
2019-05-15  1:00                         ` Arvind Sankar
2019-05-14 15:19               ` Andy Lutomirski
2019-05-14 16:33                 ` Roberto Sassu
2019-05-14 16:58                   ` Greg KH
2019-05-14 17:20                     ` Roberto Sassu
2019-05-15  0:25                       ` Arvind Sankar
2019-05-14 19:18                 ` James Bottomley
2019-05-14 23:39                   ` Rob Landley
2019-05-14 23:54                     ` James Bottomley
2019-05-15  0:52                       ` Arvind Sankar
2019-05-15 11:19                         ` Roberto Sassu
2019-05-15 16:08                           ` Arvind Sankar
2019-05-15 17:06                             ` Roberto Sassu
2019-05-16  5:29                               ` Arvind Sankar
2019-05-16 11:42                                 ` Roberto Sassu
2019-05-16 13:31                                 ` Mimi Zohar

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